Stored-program controller with means for connecting multiple plug-in functional units to a corresponding array of plug-in positions connected together by multiple address lines

ABSTRACT

An arrangement with a plurality of plug points which are interconnected via a system bus having data and control lines, address lines taken to connections of the plug points, one of which is connected to a selector terminal, and plug-in functional units, at least one of which has contacts for connecting the address lines to this unit and each of the remaining functional units has contacts for connecting the unit to the selector terminal of the plug point. Units performing read and write functions can be fitted at any plug point in such an arrangement. The invention is applicable in store-programmable controls.

BACKGROUND OF THE INVENTION

The present invention concerns an arrangement with a plurality of plugpoints and a plurality of plug-in functional units.

In stored-program controls, generally one or more central subassembliesand a plurality of functional subassemblies, for example subassembliesfor digital or analog input and output of signals, are interconnectedvia a system bus having address, data, and control lines. Thesubassemblies are fitted into plug points of a central or expansionunit, and means for address coding and decoding are provided in orderfor the functional subassemblies to be addressed by the centralsubassemblies during read or write functions.

To allow address coding to be dispensed with, it is proposed in EuropeanPatent Application 0 486 818 to provide one line each between a controlunit and individual modules of a control system. The control unitaddresses the modules by transmitting different data words over theselines. An addressing system of this kind, in an arrangement with plug-infunctional units, means that a special plug-in position which executesread and write accesses to other functional units must be provided forthe functional unit.

SUMMARY OF THE INVENTION

The present invention provides an arrangement of the aforesaid kind inwhich a functional unit executing read and write accesses can be fittedinto any plug point.

In accordance with the present invention such an arrangement includes aplurality of plug points that are interconnected via a system bus havingdata and control lines; address lines taken to connections of the plugpoints, one of which is connected respectively to a selector terminal ofa plug point; and plug-in functional units, at least one of which hasmeans for connecting the address lines to this unit, and each of theremaining functional units has means for connecting the unit to theselector terminal of the plug point.

In an embodiment of the invention, in order to transfer subaddresses theplug-in positions are interconnected via an address bus. As a result,for example, different memory regions of the functional units areaddressable.

The arrangement according to the present invention is used in particularin a stored-program control, preferably in a stored-program control witha central unit and at least one expansion unit, which are interconnectedvia a connecting cable which has the system and address bus, the addresslines, and further address lines for addressing the expansion unit.

BRIEF DESCRIPTION OF THE DRAWING

The invention and its embodiments and advantages will be explainedfurther with reference to the drawing, in which an exemplary embodimentof the invention is illustrated.

The FIGURE shows a schematic circuit diagram of an arrangement with plugpoints.

DETAILED DESCRIPTION

SP1-SP4 designate plug-in positions which are interconnected via asystem bus SYB having eight data lines and eight control lines. Addresslines AL1-AL4 are taken from plug-in position to plug-in position atconnecting means of these plug-in positions, of which first address lineAL1 is connected, via a line SL1, to a selector terminal AN1 of plug-inposition SP1. Address lines AL2, AL3, and AL4 are correspondinglyconnected via lines SL2, SL3, and SL4 to selector terminals AN2, AN3,and AN4 of plug-in positions SP2, SP3, and SP4. Functional units FE1-FE4can be fitted arbitrarily into plug points SP1, . . . , for whichpurpose functional units executing read and write functions must beconnectable to all address lines AL1-AL4 in order to address theremaining functional units. In the present example, functional unitsFE1, FE3 access units FE2, FE4 for read or write purposes. For thispurpose, functional units FE1 and FE3 have means, for example in theform of blade or spring contacts, of making a connection V1, V3 to theconnection means of the plug points and thus to address lines AL1-AL4.The addressable functional units FE2 and FE4 also have means in the formof a spring or blade contact, by means of which selector terminal AN2,AN4 of plug points SP2, SP4 makes contact with functional units FE2,FE4. Functional units FE1, FE3 address functional units FE2, FE4 with asignal, for example a logical "1," via address lines AL2, AL4 andselector terminals AN2, AN4. Functional units FE1, FE3 can address oneanother via lines AL1, AL3 and selector terminals AN1, AN3.

To allow different regions of a functional unit FE1, . . . to beaddressed, an address bus AB is provided, which in the present case haseight address lines and interconnects plug-in positions SP1, . . . SP4.With this 8-bit wide address bus, accesses are possible to 256 differentregions of a functional unit addressed via address lines AL1, . . . .AL4.

What is claimed is:
 1. A system comprising:a plurality of plug-inpositions each having connection means and a selector terminal; a systembus having data and control lines interconnecting said plurality ofplug-in positions; address lines coupled to the connection means of theplug-in positions, each is additionally connected, via a correspondingline, to the selector terminal of a corresponding plug-in position; anda plurality of plug-in functional units, at least one of which has meansfor connecting the address lines to this unit, and each of the remainingfunctional units having means for connecting that unit to the selectorterminal of the corresponding plug-in position; wherein at least one ofthe plug-in functional units that are connected to the address lines isa functional unit capable of executing read and write operations.
 2. Thesystem of claim 1, wherein to transfer subaddresses, the plug-inpositions are interconnected via an address bus.
 3. A store-programmablecontrol with a central unit having in each case an arrangement accordingto claim 2, and at least one expansion unit, which are interconnectedvia a connecting cable which has the system and address bus, the addresslines and further address lines for addressing the expansion unit.
 4. Astore-programmable control including a system comprising:a plurality ofplug-in positions each having connection means and a selector terminal;a system bus having data and control lines interconnecting saidplurality of plug-in positions; address lines coupled to the connectionmeans of the plug-in positions, each is additionally connected, via acorresponding line, to the selector terminal of a corresponding plug-inposition; and a plurality of plug-in functional units, at least one ofwhich has means for connecting the address lines to this unit, and eachof the remaining functional units having means for connecting that unitto the selector terminal of the corresponding plug-in position; whereinat least one of the plug-in functional units that are connected to theaddress lines is a functional unit capable of executing read and writeoperations.
 5. A functional unit capable of performing read and writefunctions, comprising:first connecting means for connecting saidfunctional unit to at least one of a plurality of plug-in positions,each of said plurality of plug-in positions including connection meansand a selector terminal, said plurality of plug-in positions beinginterconnected via an address bus and a system bus having data lines andcontrol lines, said plurality of plug-in positions being furtherinterconnected via a plurality of address lines, each said address linebeing connected via a corresponding connection line to the selectorterminal of a corresponding plug-in position; and second connectingmeans for connecting said functional unit to one selector terminal ofone of said plurality of plug-in positions, wherein said firstconnection means connects via said address lines one of said pluralityof plug-in positions to said functional unit capable of performing readand write functions.